piston rings for sure! - if it were valve guides or seals u would get smoke only when you start it from cold or after taking off a standing start. N20 is hard on those stock cast honda rings
like the other guys said, check your compression... I'm sure it's gonna be down

 

well.. with that said, I burn off a little oil too, but when I compression tested, I am at exactly 182 psi for each cylinder - they're all exactly the same.

I'm running 9.5:1 with total seal rings and OEM head gasket. Any idea why I'd be burning off oil?

 

yeah i'm burning some oil with my turbo also but i did a compression test after my near hydrolock last time and it was 195 190 190 190 so i'm not too worried. I also just dynoed 176 whp 173 wheel torque on 8 psi which are pretty healthy numbers so i should be ok

But dumping an extra quart of mobil 1 in every once in a while is getting expensive.

Nitrous is pretty harsh on your motor, i used to spray a 55 dry zex kit like you too and i burned oil back then also, not to mention shooting fireballs out of the exhaust (which destroyed my stock cat)